1. Field of the Invention
The disclosure relates to a catalyst retainer for a radial flow reactor, and more particularly to a radial flow reactor catalyst retainer having a louver in the catalyst seal area.
2. Description of the Related Art
Hydrocarbon conversion processes are common in the refining and petrochemical industry. For example, the production of an alkylene (e.g., propylene) can be obtained by the dehydrogenation of an alkane (e.g., propane) through catalytic dehydrogenation in a radial flow reactor. The reactants in a radial flow catalytic dehydrogenation process pass through a reaction zone containing catalyst in a substantially horizontal direction in the case of a vertically oriented cylindrical reactor. Often, the catalyst is retained in an annular zone between an inner particle retention device (e.g., an inlet screen) and an outer particle retention device (e.g., an outlet screen) in the forms of inner and outer cylinders, respectively. The devices form a flow path for the catalyst particles moving gradually downward via gravity, until they become spent and must be removed for regeneration. The devices also provide a way to distribute gas feeds to the catalyst bed and collect products at a common effluent collection zone. When the radial fluid flow is away from the center of the reactor, the passage of fluid is radially through a first retention device (inner screen), the bed of catalyst particles, and through a second retention device (outer screen).
Certain problems with radial flow reactors have been recognized. For example, U.S. Pat. No. 5,130,106 discusses the phenomenon of void blowing in a radial flow reactor. Void blowing involves the creation of a void in a catalyst bed wherein the void allows catalyst particles to blow around and create catalyst fines. Void blowing can be caused by an overall upward displacement of the catalyst bed. U.S. Pat. No. 5,130,106 describes one means to eliminate upper displacement of a catalyst bed by providing sufficient resistance to upward pressure. Specifically, catalyst particles that counteract upward pressure are located in a blanked-off section of the screens. The blanked-off section is an area above the screen openings. This means that there is little gas flow through the catalyst particles in this section of the catalyst bed. Friction between the particles and the interior walls increase the necessary pressure to upwardly displace the particles. Furthermore, the particles are added to the blanked-off section of the screens creating a catalyst seal surface in the blanked-off area.
In some catalytic dehydrogenation radial flow reactors, plugging and pressure drop buildup within the catalyst seal area and the outer screen of the reactor may be observed. This mechanism may increase the operating pressure which in turn may lead to lower paraffin to olefin conversion rate.
Therefore, what is needed is an improved radial flow reactor having a catalyst retainer that minimizes plugging and pressure drop buildup within the reactor.